The present invention relates to a device and method for testing a seal and, in particular, to a device and method for testing the integrity and strength of a seal.
In the field of packaging, the use of materials such as thin plastic films has become a commonplace technique. In this type of packaging, the product to be packaged is oftentimes placed in one film, which may or may not be pre-formed into a desired shape, after which a second film is applied to the first film with a seal being formed between the two films. For instance, this type of packaging has been used extensively in the meat packaging industry, among many others. In this type of packaging, the product to be packaged is therefore oftentimes of a perishable nature, which may or may not require vaccum packing, but the seal must in any case have the requisite integrity and strength to withstand shipment and handling through the time of reaching the ultimate consumer. While the developments in such packaging have been significant, the need for effective devices and methods for the testing of seals has remained.
In this connection, there have previously been two principal techniques for the testing of seals. One technique utilizes laser beam scanning to identify and reject packages having a faulty seal caused by dirt or other impurities. Another technique is to inject a package with carbon dioxide prior to forming a seal. This technique utilizes a vacuum chamber into which a package may be placed to measure for carbon dioxide escaping through a defective seal caused by various packaging imperfections. While these techniques work to a limited degree, neither is completely satisfactory for a number of reasons.
Specifically, neither laser beam scanning nor carbon dioxide injection is entirely satisfactory as a seal testing technique. Laser beam scanning requires the use of extremely expensive equipment which, while effective for its intended purpose, does not have the requisite versatility required in package seal testing. For instance, while it is effective to detect impurities in a seal such as dirt and the like, other potential seal defects can escape detection utilizing this seal testing technique. Carbon dioxide injection also requires the use of extremely expensive equipment which, while again effective for its intended purpose, also does not have the requisite versatility required in package seal testing. In fact, neither laser beam scanning nor carbon dioxide injection is suitable for anything more than making a periodic check of package seals on a spot-check basis and, even then, the spot-check tests only the integrity, not the strength, of the seal of the relatively few packages tested.
Accordingly, it is an object of the present invention to provide a device and method for testing the integrity and the strength of a seal of a pre-sealed package.
Another object of the present invention is to provide a device and method of the type described which utilizes equipment which is relatively simple and inexpensive.
A further object of the present invention is to provide a device and method of the type described which utilizes equipment that is capable of operating on an assembly line basis.
An additional object of the present invention is to provide a device and method of the type described which utilizes equipment which employs mechanical principals of operation to test the seals of pre-sealed packages.
Still other objects, advantages and features of the present invention will become apparent from a consideration of the detailed description and illustration set forth in the accompanying specification, claims and drawings.